The present invention relates to wiper blade cleaning systems for nozzle faces of ink jet printheads, and more particularly, to automatic positioning of the dimension between the printhead nozzle face and the wiper blade holder to control the contact dimension of the distal ends of the wiper blades.
An ink jet printer of the so-called "drop-on-demand" type has at least one printhead from which droplets of ink are directed towards a recording medium. Within the printhead, the ink may be contained in a plurality of channels and energy pulses are used to cause the droplets of ink to be expelled, as required, from orifices at the ends of the channels.
In a thermal ink jet printer, the energy pulses are usually produced by resistors, each located in a respective one of the channels, which are individually addressable by current pulses to heat and momentarily vaporize ink in the channels which contact the resistors. Operation of a thermal ink jet printer is described in, for example, U.S. Pat. No. 4,849,774.
It has been recognized that there is a need to maintain the ink ejecting orifices of an ink jet printer, for example, by periodically cleaning the orifices when the printer is in use, and/or by capping the printhead when the printer is out of use or is idle for extended periods. The capping of the printhead is intended to prevent the ink in the printhead from drying out. There is also a need to prime a printhead before use, to ensure that the printhead channels are completely filled with ink and contain no contaminants or air bubbles. Maintenance and/or priming stations for the printheads of various types of ink jet printers are described in, for example, U.S. Pat. Nos. 4,855,764; 4,853,717 and 4,746,938 while the removal of gas from the ink reservoir of a printhead during printing is described in U.S. Pat. No. 4,679,059.
The priming operation for a printhead usually involves either forcing or drawing ink through the printhead nozzles, and this operation can leave some ink on the nozzle face of the printhead. A build-up of ink residue on the printhead face has a deleterious effect on print quality. It has also been found that paper fibers and other foreign material can also collect on the printhead face while printing is in progress and, like the ink residue, can also have a deleterious effect on print quality. U.S. Pat. No. 4,853,717 discloses that a printhead is moved across a wiper blade at the end of a printing operation so that paper dust, ink residue, and other contaminants are scraped off the nozzle face before the printhead is capped. U.S. Pat. No. 4,746,938 discloses an ink jet printer that provides a washing unit which, at the end of a printing operation, directs water at the nozzle face of the printhead to clean the nozzle face before it is capped.
U.S. Pat. No. 5,151,715 to Ward et al. discloses a printhead wiper for ink jet printers molded from an elastomer and including a wiping beam having a wiping edge formed at one end of the beam. The other end of the beam is integral with a base. A hole through the beam near the base decreases beam stiffness. A higher durometer elastomer may thus be used without applying excessive wiping force to the printhead. In another embodiment, the wiper includes a pair of wiping blades each of which have wiping edges for wiping a printhead traveling thereby. The first wipe removes pooled ink and debris and spread viscous ink while the second wipe furthers the spread of ink before it can retract to its former drop or pooled configuration.
U.S. Pat. No. 4,364,065 to Yamamori et al. discloses a nozzle moistening device to prevent clogging of the nozzle of an ink jet writing head, which includes an elastic enclosure fluid-tightly engageable with the front face of the writing head when not in use, a source of water, and a capillary tube for transmitting water from the source to the enclosure by capillary action to permit evaporation of water in the enclosure to moisten the nozzle.
U.S. Pat. No. 5,250,962 to Fisher et al. discloses a movable priming station for use with a full width array ink jet printhead. A support having a vacuum nozzle has the capability of being moved along the length of the printhead and adjacent the nozzle face thereof. The support is controlled so that the vacuum does not contact the nozzle face, when the support is moved. The support has members which slidingly contact the nozzle face, but the contact is not in the vicinity of the nozzles.